Chris Cowell

CraigD. When the tolerances were defined for the Pinto Rig, the plan was to keep the sheave as close to the side plate as possible because we wanted to limit the probability of a throw line getting caught in that space. In reality, I think we were a little too adventurous, and the rubbing that you, and some other people, are seeing is because the tolerance, on occasion, is too tight. This issue only applies to the first two batches made, and has already been addressed on the subsequent production runs. DMM test for clear rotation at WLL during production, and all has been fine, but there are tolerances, and obviously some Pinto Rigs are not functioning as anticipated. For info, all returned pulleys have been analyzed and tested. All have exceeded the quoted MBS by some considerable margin, and the bearings were intact and fully functional. I would suggest returning your pulley to the retailer where you purchased it, and they will handle the procedure from there. DMM will analyse the issue with your pulley and then either issue a replacement or rebuild the pulley with the narrower sheave. The bearings in the Pinto Rig are somewhat over specified, so I doubt that there has been a bearing failure, although it is possible. But of course without seeing your Pinto, I can not make a judgement. Sincere apologies for the inconvenience you are experiencing. I know that DMM have already acted to sort this tolerance issue. Chris

Just a quick comment. You can use all versions of HC as part of a friction hitch based work positioning system. For those climbers using a low 'base friction' hitch, such as a well configured VT, and who have either an instinctive or acquired sense for these things, the increased efficiency of the HC Rapide will be very noticeable. The whole philosophy behind the HC was to try to 'normalise' hitch function as far as possible across all work, hauling and rescue situations. Reducing friction as the rope fairleads into the hitch is one way to help achieve this goal. Sheave efficiency can be very important here. Rounded edges and the correct profiling of the side plates also helps. If you have the time to wade through all the text, much of this type of thinking is outlined in the 'Hitch Climbers Guide to the Canopy', a download from the Treemagineers site (treemagineers.com). Sure enough, the HC can be 'just a pulley'. But it can also be more than that if you choose to explore more than just the basics. Chris

The ring on the bridge of a treeMOTION is rated at 30kN. Assuming both rescuer and casualty are connected to this ring, the harness continues to be subjected to a one person load. It is the work positioning system of the rescuer and the bridge ring of his/her harness which carries a 'double' load. For this reason, the ring has a rating which is double the rating required by the work positioning harness standards. Chris

The rigging plate holes in Hitch Climber pulleys are 16mm diameter so you shouldn't need to make modifications to connect a 13mm rope in the way you appear to desire. Correct that ISC Mongoose karabiners are not compatible with Hitch Climbers. However for fans of ISC connectors, the Gecko and Gator work fine....depending on what you are planning to do with the system. A number of HMS karabiners also work fine with Hitch Climbers e.g. DMM Fat Boy and the three different backs of DMM Boa. Chris P.S. feel free to contact Treemagineers directly for more discussion.

Rupe You are looking at a lowerable basal anchor for a SRT ascent line! There is an adjustable sling around the bottom of the pine. The white/green rope has a Prusik loop on it (the black/green cord) which is girth hitched into one of the slots of the small Hub. Once the ascent line is set, a bite of rope is passed through the inner of the Hub and a karabiner is passed through the bite. The tail of the ascent line can then be tied off (e.g. two half hitches) and the Prusik is blocked so that it can not slip. Should it be necessary to lower the climber during ascent, the small green Prusik acts as a backup to the friction device which has been created by the ascent line passing through the Hub and over the karabiner. This application demonstrates three generic attachment options for Hubs: 1) stationary textile (e.g. the girth hitched Prusik cord); 2) running textile (e.g. the ascent line through the inner ring); and 3) connectors (e.g. the single oval karabiner) There is a bit more info about Hubs on the manufacturer's website: http://www.dmmindustrial.com/downloads/DMM-1804_Hubs_Info_Sheet_A.pdf As you suggested Rupe, Hubs are anchors that can be configured in a number of ways in addition to using them as conventional rigging plates. Chris

ISA and AA. Both could step it up a bit. If I had to choose one, the decision would be easy - AA. UK based and UK focused......despite what most arbtalkers seem to think.

I'll be there Bob....

Drew Treemagineers tested a range of ropes in the 'O-Rig' format before describing the technique in the Hitch Climbers Guide to the Canopy. All tests used green DMM aluminium rings with a circular cross section of 12mm as an anchor at the 'climber' end of the system and a steel bollard of 110mm diameter at the other end . The lowest (static) breaking strength was 37kN which was recorded when the rope slid across the steel bollard and was cut when it crossed over a sharp edge/small bend radius. For reference, the tread diameter of a DMM Revolver is 11mm. Whilst this small difference in diameter may seem insignificant, there will be occasions when test results show otherwise. I have no doubt that on this occasion, the configured strength of an O-Rig with a locking Revolver will be sufficient, even with a small diameter climbing line. But Treemagineers have not tested this. Can I ask you to share with us the test data which allowed the NZTCC Technical Committee to allow this configuration following a period of reluctance? Chris

I've used a Trango cinch on my lanyard for a while now. Compact, easy to adjust (single or doubled rope) and releases under load - great! The Cinch does seem to be super sensitive to rope diameter however. We've done some testing on Cinch's over the last few years and confirmed what the manufacturer says about rope choice i.e. it is very important to use a dynamic rope. Impact forces from drop tests on low strecth rope can do bad things to the Cinch. Personally, I use Mammut Supersafe 10.2mm: Supersafe 10,2 mm - Single Ropes - Mammut

We seem to be on the verge of running three discussions at the same time. The thread started with a question about kN rating for tree climbing gear (Work Positioning), then rock climbing was added and now we have fall arrest! Does anyone want to discuss work restraint also?! Tim. I've seen many tree climbers accumulate far too much slack, sometimes they are on VT's but other times a Blakes or Prusik. In my early VT days I didn't always manage slack in the way I should have. Undertsanding the consequences, acquiring skills and exercising self discipline are key here. Bad practice is difficult to legislate against.... The test shown in the video is a dynamic strength test for EN361 i.e. a PPE standard covering full body harnesses that may be used for fall arrest. On a work site, energy absorbers (e.g. certified to EN355) should be incorporated into fall arrest systems to reduce the forces experienced by a climber in the event of a fall. Part of the definition of fall arrest is that there must be a clear zone to fall into. Fall arrest is not a system we can adopt in trees because of the proximity of objects that could be contacted by a climber during a fall e.g. branches, stubs, the ground. Therefore, it is up to each climber to manage their system to ensure excessive slack is not created i.e. take resonsibility. Anyone who saw the ascent demo at last years Trade Fair will know that this topic (work positioning/fall arrest/clear zones) was touched upon. For info, there will be an updated version of the Hitch Climbers Guide at treemagineers.com on or around 20th April. There is a section entitled 'Managing Slack' which shows a few techniques to help to manage out slack when work positioning in trees. In that way, there should be no reason to experience anything like the peak force created in the video drop test. Ray. I'm still keen to understand how 12kN is possible in rock climbing. Chris

Ray I've been trying to work out how it is possible to generate 12kN in a rock climbing scenario (Klettersteig excluded). What with the knots, dynamic rope, potentially a number of hardware placements and a mobile belayer, I can't picture how that force is achieveable. I asked around a bit, and 4-7kN was the consensus. Could you enlighten me please? 12kN would hurt alot...... Chris

Sciadopitys One key point about the strength of PPE is that your death shouldn’t be caused by its’ failure. Or to put it another way, you should be dead before it fails! Whether a pulley is rated to 24kN or 31kN is largely irrelevant, because anyone attached to it is likely to be cream crackered long before that force is reached. Another point to consider is that manufacturers adopt their own margins of safety. A product rated to 22kN may fail just above, or significantly above, that force depending on company philosophy. In the case of the Hitch Climber, the breaking load is 10+kN higher than its’ rated strength. CE/EN is a system that demands independent verification by a notified body. Many US products that carry an ANSI marking may be self certified by the manufacturer. It is my understanding that there is often no requirement for independent verification for PPE products sold in the US market. However, the last thing a manufacturer wants is a claim resulting from an accident, so they are unlikely to make false claims. My point is merely that the two systems are not the same, and of course neither is perfect! One system is, however, clearly more expensive to administer than the other and its’ presence is a legal requirement if you want to sell PPE within the EU.

What a great question to start a thread with! I have never understood why our industry guidance says 22kN. To me there appears to be no complete logic to it. The two EN standards for connectors (EN362:2004 PPE Connectors; EN12275:1998 Mountaineering Connectors) tend to suggest that 20kN would be a sufficient major axis strength. Harnesses certified to EN358 and EN813 are required to have static strengths of 15kN. Equally, terminations (knotted, spliced or stitched) in EN1891A rope have to have a static strength of 15kN. So surely 15kN would be OK for a karabiner that either directly or ultimately connects to a harness/rope? However, EN566 (slings) requires 22kN partly because of the potential for strength loss through abrasion. My assumption is that our industry has adopted 22kN to keep things simple i.e. one number for all components. Because it is relatively easy to manufacture/source PPE with these high breaking loads, a high number is specified. I’m guessing that if it were more difficult to achieve 22kN, our industry would be happy to accept 15kN…..which is more than enough to ensure a sticky ending! Generally speaking, a pre-configured strength of 22kN is sufficiently high to ensure that when the component (e.g. rope) is configured (e.g. knotted), the retained strength is still above the magic 15kN. Maybe industry guidance should state that all systems must have a minimum configured strength of 15kN?